Carsten: I think that to see an Aikido technique as irresistable no matter what uke does can't be right. What you're saying is that even when uke KNOWS what is going to happen and is allowed to resist, nage should be able to effortlessly do the technique if he's skilled enough.

I think that goes against the grain of what Aikido is. You work with what your uke gives you, so if he is resisting against one technique, you just do another one which his resistance makes him weak too. That's what Aikido is, using his resistance against him and different Aikido techniques are specific ways to deal with certain kinds of resistance.

What is the 'right' Aikido technique to do changes on what he gives you. So yes a 'right' Aikido technique will always work, but that doesn't mean you can apply a specific technique no matter what the resistance is, since it will be then the wrong technique for that situation.